I recently brought a iBasso T5 n found that the voice had been distorted, not as good as directly plug into my J3...I've tried every single cables in all headphones stores in my local place, but none of them really helps...my combination is Cowon iAudio J3 + Germany Silver Plated Cable with ViaBlue Plug + iBasso T5 + Ultimate Ears 900. The voice used to be more clear when I directly plug my iem into my J3, but with the amp...
Edit: I used to use EQ, but I'm using normal EQ this time...strange...worst than my J3...